Can you provide a bit of clarification or an example of what you mean by ‘Medical Benefit ID’?
If you’re referring to the subscriber member number, then the field to look at would be coverage.subscriberId. If you are referring to the patient member number the corresponding field would be coverage.dependent. If the subscriber is the patient, then the subscriberId and dependent would match.
For ‘Group Id’, I would think you are looking for the group number which would be the coverage.class.value, when the coverage.class.type.coding.code is group.